The objective of the proposed research is to determine thermodynamic parameters for specific protein-nucleic acid interactions. Initial research will focus on the lac repressor-lac operator system. Later research will be directed toward the lambda cI repressor-lambda operator complex. Characteristic reaction properties of these complexes will be investigated. Specifically, the stoichiometry of the binding process, the heat of reaction, the number of protons released upon binding, and the effect of temperature and solution conditions on these parameters will be examined. The technology necessary for measuring these parameters is presently available. Thermodynamic properties will be measured using a new nanocalorimeter that is being built for this research. The DNA will be prepared using recombinant DNA plasmids that contain chemically synthesized operator.